1. Technical Field
The present disclosure relates to an illumination light source for use in an outdoor illumination apparatus or a vehicle headlight, and to an illumination apparatus for outdoor use or vehicle headlight use.
2. Description of the Related Art
Illumination apparatuses which use light-emitting diodes (LEDs) are conventionally used.
In order that illuminating light emitted from the illumination apparatuses is perceived as bright, under a photopic environment, photopic luminance of the illuminating light may be increased. In this regard, in order that the illuminating light is perceived as bright under a mesopic environment such as night street spaces and night road spaces, scotopic luminance also needs to be considered. Japanese Unexamined Patent Application Publication No. 2013-101881 discloses an illumination apparatus (a vehicle headlight) which emits illuminating light that is perceived as bright with peripheral vision under a mesopic environment, by increasing the S/P (scotopic/photopic) ratio which is a ratio of a scotopic luminous flux to a photopic luminous flux.